Method and apparatus for evaluating the cognitive performance of an individual

ABSTRACT

A method for evaluating the cognitive performance of an individual by qualitative/quantitative analysis of the performance of a task, characterized in that: The task is a practical problem which may be exactly represented both graphically and mathematically and solved both graphically and computationally; The task has a set of solutions with a number of elements greater than one, one element being the best possible solution; And wherein the individual provides a graphical solution; Said graphical solution is converted into a numerical solution; A reference numerical solution is computed; The graphical solution converted into the numerical solution is compared with the computed reference numerical solution, a difference index being determined between the computed reference solution and the graphical solution proposed by the individual. The invention also relates to an apparatus for implementing said method.

The invention relates to a method for evaluating the cognitiveperformance of an individual by qualitative/quantitative analysis of theperformance of a task.

Such methods are known and generally consist of a set of tests to besolved by an individual. The results of the tests are evaluated againstcriteria which are mostly generated by statistic experiences.

Prior art methods are widely used in a variety of fields, e.g. forpersonal use, scientific use or job assignment, to properly addressindividuals towards job types that are appropriate for their skills, oras a medical help to obtain initial information about the possiblepresence of cognitive skill disturbances.

However, currently used methods have drawbacks mainly consisting in thestrong dependence of results from demographic parameters, such as thecultural and educational level of individuals, linguistic knowledge andother factors. As stated above, they are based on non strictlymathematical result evaluation criteria, whereby they may lead to nonpurely objective evaluations.

No method can currently obviate the above drawbacks, and allow at thesame time an easy and fast implementation.

The invention is based on the problem of designing a method such as theone described above, which allows to obviate the shortcomings listedhereinbefore, is independent from the various demographic parameters,such as cultural and educational level and from the linguistic knowledgedegree, and especially is based on strictly mathematical, henceobjective result determination procedures.

The invention achieves the above purposes by providing a method asdescribed hereinbefore, wherein the task is a practical problem and maybe exactly represented both graphically and mathematically, solved bothgraphically and computationally, which task has a set of solutions witha number of elements greater than one, one element being the bestpossible solution, and wherein the individual provides a graphicalsolution and said graphical solution is compared with a best referencesolution, at least one difference index between said best referencesolution and said solution determined by the individual being computedfrom said comparison.

In a first embodiment, the problem is always the same and the bestreference solution is precomputed.

An improvement may involve a finite set of different problems, theirrespective best reference solutions being precomputed or known.

This allows to prevent a certain performance improvement effect, causedby the repetition of the same problem several times, i.e. based on acertain experience accumulation.

In this case, the comparison between the two solutions, i.e. the bestreference solution and the graphical solution provided by the individualmay be only executed on a graphical basis, or both solutions may beconverted into a result or a set of numerical data to be compared witheach other.

An additional variant may involve the definition of a different problemfrom time to time, the graphical solution determined by the individualbeing converted into a numerical solution and later compared with thecomputed reference numerical solution, a difference index between thebest computed solution and the solution proposed by the individual beingcomputed from said comparison.

Advantageously, the type of problem may be selected in such a manner asto have a set of solutions consisting of a succession of solutionsconverging towards the best solution.

Preferably, the set of solutions has a discrete number of solutions.

In accordance with an additional variant of the invention, a variableset of solution rules may be defined, i.e. delimiting constraints tolimit the graphical and/or computational solution modes.

This allows to finely calibrate the difficulties of the problem to besolved, so that the problem may be adapted to the demographiccharacteristics of the individual, i.e. to the general culture skills orto the specific knowledge which might affect the result.

Regarding the difference index between the graphical solution proposedby the individual and the computed reference solution, it may consist ofan absolute or relative difference value or of a deviation value, suchas the standard deviation or any other value indicative of thedifference between the two values.

Still according to another characteristic of the invention, severalparameters for evaluating the graphical solution proposed by theindividual may be provided, such as the problem solving time or anyother mathematic-geometric characteristics which might be derived as aparameter of the specific graphical solution.

A variant embodiment of the method of the invention may include severalevaluation steps like those described hereinbefore, each of them beingbased on the comparison between the solution proposed by the individualand a different computed solution, which was obtained by a differentbest solution computation algorithm and/or a different best solutionamong the available solutions, the comprehensive evaluation consistingof a combination of said evaluation steps, possibly appropriatelyweighted.

Advantageously, the proposed problem is such that it has a set ofsolutions SOL, whose elements S_(i) consist each of one or more possiblecombinations of different solving steps p_(n) which may be executed indifferent execution orders.

Particularly, the set of solutions SOL may consist of elements S_(i)each comprising one of the possible permutations of the steps p_(n)within a succession or sequence of steps.

Moreover, still advantageously, the proposed problem is such as to allowa difficulty adjustment, the number of steps and the number ofcombination permutations of said possible steps being selectable. Inthis case, the variable number of steps n defines the difficulty of theproblem both as a graphical solution and as a mathematical solution.

The solutions S_(i) consist of a function F of the steps p_(n) belongingto the corresponding sequence of the n steps p_(n), said function takingdifferent values depending on the selected permutation order of the nsteps p_(n). This function F(p_(n)) is selected in such a manner as tobe an easily executable mathematical and graphical operation, whereasthe difficulty is defined in the increasing number of possiblepermutations, in a typically exponential function.

According to a further variant, the type of problem proposed isadvantageously such that each preceding steps qualitatively andquantitatively affects at least the next step, or even severalsucceeding steps.

The method of the invention involves the graphical representation of thepractical problem on a video screen and the graphical solution of theproblem on said screen by graphically performing the single steps insuccession. Then, the graphical solution is converted into thecorresponding numerical value and compared with the reference solutionobtained by mathematical computation.

A correlation table may be determined with the help of calibration testson sample individuals having known cognitive performances, to interpretthe deviation or difference index between the value of the solutiongiven by the individual and that of the computed reference solution.

According to the invention, a typical problem is the so-called TravelingSales Person Problem.

The Traveling Sales Person Problem consists in defining a list of sitesarranged over an area, which sites have different locations, and have tobe visited by the Traveling Sales Person, whose role is taken by theindividual. The individual has to choose the sequence of the sites to bevisited in such a manner as to minimize the total length of the path.

From the graphical point of view, in this case, the method involves thedefinition of an at least two-dimensional space, wherein the locationsare defined by points distributed over this space, whereas the graphicalsolution consists in drawing the route to minimize the global lengththereof, in the form of point connecting segments.

The mathematical description consists in the definition, by an at leasttwo-dimensional reference system, of the different locations, in theform of at least two coordinates for each location, whereas the solutionof the sequence of connection segments between individual points iscomputed on the basis of the mathematical determination of the distancebetween successive points and corresponds to the sum of the individualdistances of successively connected points, according to the sequence ofsuccessive points which provides a minimum value of the sum of theconnecting segments. In this case, the path minimization solution mustbe determined by computing all the possible sequences, hence bycomparing the obtained path lengths and determining the smallest one.

With reference to this problem, it is apparent how the latter ismathematically trivial, but extremely complex from the computationalpoint of view, even when considering a relatively small number ofpoints, such as 10 or more points. Here a very great number of possiblesequences is provided, the number of possible permutations of theindividual steps being an exponential function of the total number ofsteps.

Referring to the general characteristics of the method of the invention,a fixed point distribution pattern may be provided or a set of differentpoint distribution patterns, the best reference solution being known foreach pattern.

Alternatively, the solution may be computed from time to time, the pointdistribution pattern being determined all over again at each methodexecution.

The distribution pattern may be generated, for instance, by means of arandom generator of point coordinates.

To obviate the drawback caused by excessively long computation times,the method of the invention involves that the solution, i.e. thedetermination of the shortest path, be computed by so-called geneticalgorithms, such as those described, for instance in “Reti NeuraliArtificiali e Sistemi Sociali”, page 465-486, 21. Genetic DoppingAlgorithm, by Massimo Buscema, Edizioni Franco Angeli Milano 1999.

The problem is solved by the user in a purely graphical manner and basedon perception and visual estimate, as well as on short-time memoryskills and on heuristic bases.

The solution essentially consists in drawing straight lines to connectthe individual points of the selected sequence.

The conversion of the graphical solution into path length is trivial perse since, after defining a connection sequence for successive pointswhich are uniquely defined by coordinates in a two-dimensional space,such conversion requires a simple distance or length determination.

Several graphical problem solving rules may be provided, such as:

-   -   Each point shall be connected by two half lines    -   Each point cannot be hit more than once    -   All points shall be hit.

These different rules or delimiting constraints allow to calibrateproblem solving difficulties as desired without changing the number ofpoints.

Alternatively to or in combination with the above, other parameters maybe provided for the comparison with the best reference solution, i.e.with the shortest path solution. These parameters may be, alternativelyor in combination, the number of crossovers or hits through one point,the solving time, the path segment drawing order, the determination ofthe areas of polygons defined by drawn segments and by crossovers and/orthe determination of the total area of the surface enclosed by the drawnpath, as well as comparisons between said two area values or othercharacteristics of the solution to be parametrized graphically ormathematically.

It is also possible to evaluate one or more of the above parameters withreference to one or more best solutions, which are predefined and/orcomputed with the help of different algorithms. In this case, thesolution is given by a combination of the individual, possibly weightedevaluations.

The above is possible because, for mathematical problems such as the onedescribed above, i.e. the so-called “Traveling Sales Person” problem andfor similar problems, several types of computation algorithms exist,even within the family of genetic algorithms. These algorithms may havedifferent performances, for instance times for obtaining the best resultbut also modes for computing the algorithms, whereby some algorithms maybe more appropriate than others for evaluating the geometriccharacteristics of the solution proposed by the individual.

Based on the above, the method according to the invention consists in:

-   -   Defining an at least two-dimensional space according to a        predetermined coordinate system;    -   Defining the number of points to be distributed in said at least        two-dimensional space;    -   Uniquely identifying the position of each of said points        distributed over said space with at least two coordinates        determined by random generation;    -   Displaying a graphical representation of said at least        two-dimensional space and of the points distributed thereon;    -   Generating a succession of point connecting lines in a point        connection sequence selected in such a manner as to minimize the        total length of the sum of the individual segments connecting        successive pairs of points of said point connection sequence,        only based on visual evaluation;    -   Determining the sum of the segments connecting successive pairs        of points, on a graphical/visual basis, based on the graphically        defined point connection sequence;    -   Comparing the graphically defined total sum of the point        connecting segments, with the total sum of the connection        segments of a best reference solution, i.e. a point connection        sequence through segments, which minimizes the total sum of the        point connecting segments, and determining a difference index        based on deviation measurement algorithms, such as absolute        difference, relative difference and/or standard deviation and/or        other algorithms for estimating differences between values.

Said reference solution may be known and precomputed or computed whilethe graphical solution is provided.

Therefore, the deviation or difference index obtained thereby may beinterpreted by comparison with a table which relates difference indexesand performance evaluation, to be obtained, as stated above, fromcalibration tests.

According to an additional step, a graphical/visual comparison may bealso performed between the computed solution and the one which has beengraphically/visually determined by an analysis of the congruence of saidgraphical/visual solution to the graphical representation of thecomputed solution.

It shall be noted that the specific Traveling Sales Person Problem, orany other similar problem may be also extended to three- orn-dimensional spaces.

In these conditions, besides a highly objective evaluation based on thedifference index, an evaluation may be provided of the logic of theroute selected by the user to perform his/her task.

From the above description, the advantages obtained by said method areself-evident. In fact, no particular linguistic or technical knowledgeis required to carry out the task, but both the type of task and thesolving method are compatible with primitive tools, available to anyindividual.

The linguistic knowledge, required to communicate with the individualare limited to little easily understandable information only required toexplain the task to be performed and the possible use of means to drawthe selected route.

Regarding task performance, the task may be carried out in a short timeand the use of genetic algorithms for computing the route minimizationsolution allows to drastically reduce the computation time and to choosea sufficient number of points to be successively connected to obtainthat the proposed problem is not trivial for persons having a higheducational level, for instance as regards geometric knowledge or workexperience.

Therefore, the problem is optimal both for its wide understandability byuneducated individuals, and for the possibility to calibratedifficulties in such a manner as to drastically limit the usagepossibility or the incidence on the result by individual-baseddemographic parameters, such as specific knowledge of people having ahigh educational level, either in general or in specific fields.

The invention also relates to a method for screening and monitoringcognitive disturbances or diseases.

Particularly, the invention relates to an Alzheimer disease earlyscreening and monitoring method.

The provision of an early screening and monitoring method is extremelyimportant. When considering Italian population only, in whichover-sixty-five people are more than 20%, 800,000 cases of dementia areestimated, about 500,000 being attributable to Alzheimer disease. Inspite of the importance of dementia as a Public Health problem,standardized evaluation approaches are not widely used in medicalpractice (Brodaty H., Howarth G., Mant A., Kyrrle S. General practiceand dementia—A national survey of Australian GPs. Med J Australia1994;160:10-14).

The possible reasons thereof include: no recognition of standardizedevaluation utility, no familiarity with the available tools, but aboveall, the limits of the commonly used tools (Camicioli R., Wild K. In“Scale di valutazione in neurologia” Centro Scientifico Editore 1998pag.125). In accordance with the guiding criteria which are generallyassumed as valid to assess Alzheimer disease cases (NINCDS/ADRDA)(McKhann G., Drachman D., Folstein M., Katzman R., Price D., Stadlan E.Clinical diagnosis of Alzheimer's disease: report of the NINCDSADRDAwork group under the auspices of Department of Health and Human Servicestask force on Alzheimer's disease. Neurology 1984;34:939-43), dementiamust be assessed by a clinical test observing an impairment in two ormore cognitive areas, or a single severe, gradually progressivecognitive deficit; a progressive loss of memory and other cognitivefunctions; no alterations of the conscious state; first occurrence at anage between 40 and 90; lack of systemic or encephalitis diseases whichmight explain the progressive cognitive decline.

No universally accepted and diagnostically applicable instrumental testsand/or biological markers are available to date. Therefore, it isessential to count on the availability of neuropsychological testinginstruments, which are standardized and calibrated on elderly people, todistinguish physiological age-based modifications of cognitive skillsfrom those associated with the starting phases of AD. An appropriate andespecially early diagnosis appears to be the only way to allow a timelyintervention, targeted on the causes of reversible dementias, and toestablish symptomatic treatments allowing to temporally delay theprogression of the dementia-based disease.

To this end, a number of neuropsychological tests which are currentlyavailable in international literature have been designed, tested andvalidated. Some of these are short screening tests, fast and easy toexecute, others are actually test batteries for evaluating upper cortexfunctions. One of the screening tests, the most widely used is the MiniMental State Examination (Folstein M., Folstein S., McHugh P.,“Mini-mental state” a practical method for grading the cognitive stateof patients for the clinician. J Psychiatric Res 1975;12:189-98), whichis composed of 11 easy tasks. Other short instruments are the ShortBlessed Orientation Memory Concentration (BOMC) (Katzman R., Brown T.,Fuld P., Peck A., Schechter R., Schimmel H. Validation of the shortorientation—memory—concentration test of cognitive impairment. Am JPsychiatry 1983;140:734-39), the Short Portable Mental StatusQuestionnaire (Pfeiffer E. A short portable mental status questionnairefor the assessment of organic brain deficit in elderly patients. J AmGer Soc 1975;23:433-41), the Mental Status Questionnaire (Kahn R.,Goldfarb A., Pollack M., Peck A. Brief objective measures for thedetermination of mental status in the aged. Am J Psychiatry 1960;(October):326-28), the Information/Orientation Test (Pattie A H,Gilleard C J. Manual of the Clifton Assessment Procedures for theElderly (CAPE). Kent, England: Hodder & Stoughton, 1979), and theAbbreviate Mental Test Score (Hodkinson H M. Evaluation of a mental testscore for assessment of mental impairment in the elderly. Age Ageing1972;1:233-8). Unfortunately, one of the major problems of the fastadministration tests is that they are quite insensitive for earlydetection of dementia, i.e. do not discriminate a demented elder manfrom a non demented elder man. This condition has been checked inseveral studies on well-known tests and the US Agency for Health CasePolicy and Research clinical Practice Guideline on recognition andinitial assessment of Alzheimer disease and related dementias (US Agencyfor Health Care Policy and Research clinical Practice Guideline onrecognition and initial assessment of Alzheimer disease and relateddementias Clinical Practice Guideline N ^(o) 19 Silver Springs, MD USAgency for Health Care Policy and Research, 1996) concluded that noevidence exists to recommend a screening test instead of another, andthat no available screening test has a high sensitivity index in thediagnosis of slight to moderate dementia.

In addition to the above problem, another problem is to be considered,because serious evaluation errors may derive therefrom. Any cognitivescreening test must be interpreted within a context of additionalinformation provided by the patient or by one of its relatives, whichmay fully or partly explain the results being obtained, e.g. culturaldifferences, educational level and premorbid skills, which considerablyaffect patient performance. A number of studies (O'Connor D. W., PollittP. A., Hyde J. B., et Al. The reliability and validity of Mini MentalState in a British community survey. J Psychiatr. Res. 1989; 23:87-96,Jorm A. F., Scott R., Henderson A. S., Kay D. W. Educational leveldifferences on the Mini Mental State: the role of test bias. PsycholMed. 1988; 18:727-731, Fillenbaum G. G., Hughes D. C., Heyman A., GorgeL. K., Blazer D. G. Relationship of health and demographiccharacteristic to Mini Mental State Examination score among communityresident. Psychol Med. 1988; 18:719-726) prove that an inverseproportion relation exists between the educational level and the risk ofdementia. There are two types of mechanisms which might cause thisphenomenon. The Brain Reserve Hypothesis postulates that individualshave a cognitive reserve in which a dementia threshold is situated; thateducation promotes the development of a more efficient brain activity,probably through the formation of more numerous or “competent” synapses;and that the occurrence of dementia is delayed in more educatedpatients, thanks to their greater cognitive resources. Conversely, theBrain-battering Hypothesis (Del Ser T., Hachinski V., Munoz D. G. Anautopsy-verified study of the effect of education on degenerativedementia. Brain 1999; 122, 2309-2319) postulates that the apparenteffect of education results from its association with the socioeconomiccondition. In fact, the socioeconomic status is the main determiningfactor of exposure to toxic industrial and non-industrial substances, aswell as of habits, such as drinking and smoking, of diet and of medicaltreatment access. Each of these factors may alter the Alzheimer diseaserisk (Munoz D. G., Ganapathy M. D., Eliasziw M., Hachinski V.Educational Attainment and Socioeconomic Status of Patients withAutopsy-Confirmed Alzheimer Disease. Arch Neurol. 2000; 57:85-89).

In order to obviate the low-sensitivity and specificity problems ofshort instruments, test batteries have been developed which investigatemore deeply into the various cognitive skills; some of these sets arebased on existing neuropsychologic tasks (Eslinger P., Damasco A.,Bentos A. The Iowa screening battery for mental decline. IowaCity:University of Iowa Press, 1984). These neuropsychological batterieswhich fully and systematically explore the main upper cortex functionsare for instance M.O.D.A., the Alzheimer Disease Assessment Scale (ADAS)(Rosen W., Mohs R., Davis K. A New Rating Scale for Alzheimer disease.Am J Psychiatry 1984;141:1356-64), C.A.M.C.O.G. of C.A.M.D.E.X. (RothM., Tym E., Mountjoy C.Q. et Al. CAMDEX. A standardised instrument forthe diagnosis of mental disorders in the elderly with special referencefor the elderly detection of dementia. British Journal of Psychiatry1986; 149: 698-709), A.G.E.C.A.T. and inside it Geriatric Mental StateExamination (Copeland J. R. M., Keller M. G., Keller J. M., et Al. Asemistructured clinical interview for the assessment of diagnosis andmental state in the elderly: The Geriatric Mental State Schedule. 1.Development and reliability Psychological Medicine 1976; 6: 439-449)These instruments potentially allow an earlier identification ofdementia, but this affects the administration rapidity. For this reasonthey are adequate especially to specially investigate the residualskills and possibly to establish a rehabilitation treatment. Moreover,since they can better evaluate the alteration of cognitive skills, theyare suitable to test the effectiveness of anticholinesteratic drugs.

Therefore, the invention has the object to design an Alzheimer diseaseearly screening and monitoring method which might obviate the drawbacksof currently known methods.

This method is based on two assumptions. The former is the assumptionthat organization and planning skills, typically associated to problemsolving tasks and characterizing the executive function, is a verysensitive indicator of an early phase of the Alzheimer disease (Elias W.J., Treland J. E. Executive Function and Cognitive Rehabilitation.Cognitive Rehabilitation in old Age, New York Oxford University Press2000). The latter is the assumption that performance against these tasksis significantly different depending on the seriousness of the disease,starting to a very slight phase (minimal dementia) to a moderate phase.

Another object of the invention consists in designing an Alzheimerdisease early screening and monitoring method, which provides theproposal of a test task, which may be administered even to individualshaving serious linguistic deficits, or to foreign patients, as itincludes no verbal interaction, except as regards the explanation of thetask, unlike all the other tests available from the literature.

Yet another object of the invention consists in that the proposed taskis not affected by the educational level, by premorbid skills, byculture and by age.

A further object is to design an Alzheimer disease early screening andmonitoring test, which also shares some typical characteristics ofculturally free tests, according to Jensen classification (Jensen A. R.Bias in mental testing, New York Free Press 1980), and particularlymeets the following criteria: power test, only figurative material,non-verbal contents, educationally-unrelated skills, new problemsolving, initial test items, responses given on the test, oral or mimedinstructions.

Yet a further object of the method according to the present inventionconsists in designing an Alzheimer disease early screening andmonitoring method, in which the proposed test task does not require theimplementation of particular strategies and the use of knowledge inabstract situations, far from everyday life and, finally, in which thetest can be completed in a short time.

The method according to the invention consists in the performance of atest, whose task is a practical problem and may be exactly representedboth graphically and mathematically and solved both graphically andcomputationally, which task has a set of solutions with a number ofelements greater than one, one element being the best possible solution,and wherein the individual provides a graphical solution and saidgraphical solution is compared with a best reference solution, at leastone difference index between said best reference solution and saidsolution determined by the individual being computed from saidcomparison.

Particularly, the test comprises any combination or sub-combination ofthe characteristics of the method for evaluating the cognitiveperformance of an individual as described above, and particularlyconsists in the solution of the so-called Traveling Sales Personproblem, according to one or any more combinations or sub-combinationsof the characteristics described above with reference to the generalmethod for evaluating the cognitive performance of an individual.

The Alzheimer disease early screening and monitoring method according tothe invention may be also provided in combination with one or more ofthe additional known tests listed above.

The method according to the invention has been tested on populations ofindividuals in a healthy state and suffering from different levels ofAlzheimer disease or by elderly dementia. The resulting data proved thatthe performance against the Traveling Sales Person Problem seems to beindependent from the visuospatial memory and is not related to the TrailMaking (A form), probably because they investigate two different typesof executive functions. The Trail Making appears as a form of guidedplanning based on the knowledge of numbers, hence it evaluates theexecutive functions within the crystallized intelligence, whereas theTraveling Sales Person problem appears as a form of free planning, i.e.within fluid intelligence. According to Jensen criteria, the TravelingSales Person problem appears to be independent from demographicvariables, which have traditionally proved to affect the performanceagainst psychometric tests, such as age, sex, educational level. TheTraveling Sales Person Problem discriminates with a high degree ofaccuracy, ill subjects from healthy subjects. Therefore, the studyallowed to find a novel screening instrument, which might be moresensitive than the previous ones, while maintaining the basiccharacteristics of short psychometric tasks. Furthermore, theperformance against the Traveling Sales Person problem with a limitednumber of points (about 30) appears to be strictly related to thecognitive state of the patient suffering from Alzheimer disease andremains easy to administer even in the moderate stage of the disease.The Traveling Sales Person Problem may be further used to monitor thecourse of the disease and to ascertain the effectiveness of drug andnon-drug interventions.

As regards both the general cognitive performance evaluation method andthe use thereof as a mass diagnostic instrument for Alzheimer disease,the selection of the task as a Traveling Sales Person Problem is not theonly possible one.

Alternatives thereto may include, for instance, the three colorsproblem, in which the cells of a grid must be colored with differentcolors from directly adjacent cells, on every side, i.e. right, left,above and below. The first column is to the right of the last column andthe top row is below the bottom row and vice versa; The particularproblem with a grid size of 5 by 5 cells allows to provide a solutionwith two colors exactly, without considering the last set ofconstraints. An example of the two-color solution is the checker board.When said constraints are considered, then the solution requires threecolors. There are at least 847,288,609,443 possible colorings and about1,000 solutions which meet the constraints.

Obviously this problem includes aspects that may be advantageous or notas compared with the Traveling Sales Person Problem. Nevertheless, thisproblem proves that problems may be provided as an alternative to theTraveling Sales Person Problem.

The method for evaluating the cognitive performance of an individual maybe also used in business fields.

The invention also relates to an apparatus for evaluating the cognitiveperformances of an individual, which apparatus comprises:

-   -   A screen displaying an at least two-dimensional area and points        distributed over said area;    -   Means for drawing segments to connect pairs of said points by        means of connection lines to be displayed on said screen;    -   An electronic processing unit with a memory containing the        algorithms for generating the at least two-dimensional space and        for generating the coordinates of the different locations, the        algorithms for generating a graphical representation of the at        least two-dimensional area and of the individual points, the        algorithms for drawing the point connecting segments and for        displaying said connecting segments on the screen, the        algorithms for determining the total length of the drawn        segments and the algorithms for pure mathematical computation of        all the point connecting segments, in a connection sequence        which minimizes the total length of said segments, as well as a        possible algorithm for alternately or adjacently displaying all        the point connecting segments, as obtained from the algorithm        for computing the reference solution, and as set by the        individual in the graphical/visual solving attempt.

Furthermore, said apparatus may comprise means for overlapped display ofall the drawn successive point connecting segments and all the computedsuccessive point connecting segments, the segments from the twodifferent sets, i.e. the drawn set and the computed set beinghighlighted in different manners, e.g. in different colors, and thecongruent connecting segments from the two solutions being highlighted,for instance with two-color, double or three color segments.

According to an additional characteristic, the apparatus may alsoinclude algorithms for determining a quantitative differentiation indexbetween the drawn and the computed sets of segments and/or betweencorresponding total lengths.

Here, storage of interpretation criteria may be also provided, based onempirically or experimentally established data tables, as well as meansfor comparing the differentiation index with said interpretation tables.

Advantageously, the apparatus may include a memory or a memory sectiondesigned for collecting and storing the sets of segments drawn by auniquely identified individual when graphically solving differentproblems with different number distributions, there being providedalgorithms for determining an average differentiation index based on theindividual differentiation indexes between the drawn set and thecomputed set, as determined during the performance of the differentsuccessive tests.

There may be also provided data for characterizing the typical data ofthe individual which have a potential influence on the test executionand may used to define parameters for weighting the differentiationindexes to account for any particular specific skills of the individualin extreme conditions.

These parameters or specific skills and the relevant effects on thedifferentiation indexes may be defined on an experimental basis andstatistically attributed to the individual depending on parameters suchas age, job type, duration of employment in that specific job, culturalor educational level or on the basis of other demographic parameters orof combinations thereof.

Moreover, said parameters may be used to define task difficultyparameters, for instance and essentially to define the number of pointsto be determined.

The above means may be of the conventional type, consisting of a simplecomputer or of a dedicated computer similar to a game pad, with theminimum of control interfaces and inputs required for task execution, tominimize any inhibiting effect generated by a traditional computer inlittle educated users.

In this case, memories are conventional computer memories and thevarious functions are algorithm executing programs, whereas the screenis the computer monitor, in both cases of traditional computers and ofgame pads.

The apparatus of the invention in the above embodiment is also highlyadvantageous in view of the integration thereof in a network forcollection, archive, and consultation of data on individuals. Furtherimprovements of the invention will form the subject of the subclaims.

The characteristics of the invention and the advantages derivingtherefrom will appear more clearly from the description of anon-limiting embodiment, as shown in the annexed drawings, in which:

FIGS. 1 to 24 show the different solutions to an example of theso-called Traveling Sales Person Problem having a number of steps n=4.

FIG. 25 shows the block diagram of an apparatus for implementing themethod according to the invention.

FIGS. 1 to 24 show a two-dimensional space defined by x and ycoordinates and in which space four points P1, P2, P3, P4 are entered,having coordinates (X_(r), Y_(t)).

The set of solutions SOL includes the solutions S_(i), each being thesum of the lengths of the connecting segments Rx, which connect pairs ofpoints in a predetermines sequence of the 24 possible sequences.

The best solution is the solution S_(i), for which the sum of thesegments R_(x) has the lowest absolute value.

As easily determined, there are 24 possible solutions S_(i) whichcorrespond to the number of possible permutations of the point Pconnection order. The various lengths of the individual lines R_(x) maybe trivially computed based on the pairs of coordinates (X_(r), Y_(t))which define the position of the points P in the two-dimensional spaceX-Y. However, this computation is not fast, since the possiblepermutations of the point P connecting sequences have 24 elements withfour points only.

The chart clearly shows how, on a merely heuristic and experience basis,a solution may be graphically generated which may be even the best whenfour points are provided, but may be anyway considerably similar to thebest solution as compared with the other possible solutions. In fact,with reference to an averagely skilled individual, the illogical orirrational connection sequences are automatically excluded, as well asthe connection sequences which, based on a minimum reasoning andexperience may be assumed as non advantageous for the purposes of tasksolving. Considering, for instance, the point P₁ as the starting andending point of the traveling salesman, then it is easy to see how, on apurely visual and logical basis, many solutions are immediately removedas requiring double routes.

In fact, the solutions having P₁ as a route starting and ending pointare to be considered preferred solutions which do not require pathduplications. These solutions are solutions S1 to S8 of FIGS. 1 to 8,S15 of FIG. 15, S17 of FIG. 17, S21 of FIG. 21 and S23 of FIG. 23.

The selection of the best solution amongst the above mentioned solutionsmay not be trivial, whereby these solutions may be considered as partsof a subset, in which the deviation of the graphical solution from thereference computed solution is relatively small as compared with otherpossible solutions.

Moreover, in the subset of solutions having P₁ as a starting and endingpoint, some solutions are relatively illogical and may be further usedto evaluate the proposed solution, e.g. based in the graphical/visualcomparison with the best solution. (See for instance the solution ofFIG. 1 and that of FIG. 2).

The complexity, i.e. the number of necessary combinations in themathematical computation of the set of solutions increases exponentiallywith the increase of the points p_(n) selected to define the problem.With ten points, the mathematical and graphical solutions are alreadyfar from being trivial, and the time to compute the various possiblepermutations for point connection sequences increases considerably.Moreover, the effect on the solution of not only cognitive but evenintellectual skills, and of knowledge, e.g. geometric knowledge is alsolimited. Nevertheless, from the graphical point of view, it is stillrather easy to identify a graphical solution which, while not being thebest one, is close, within predetermined deviations, to the best one.

When 30 points are provided, the indication of the best solution becomesrather difficult, even graphically, especially when random best solutionidentification factors are filtered off or drastically reduced, as theset of solutions statistically has a huge number of elements, wherebythe random identification of the best solution becomes statisticallyimprobable. Moreover, with 30 points being provided, the effect of theindividual's cultural and educational level on the solution is alsominimized, due to the fact that the control of the various geometricconfigurations which might provide indications on the shortest pathselection is extremely complicated. Moreover, it shall be noted that,with 30 points, the consequences on the route to be drawn are no longereasily foreseeable without a deeper analysis of the problem and withoutthe help of at least a written list of options, to evaluate theconsequences of the selections made on the path to be drawn.

Even from the computational point of view, the problem is no longertrivial, because, while the function to determine the successive pointconnecting segment lengths is computationally trivial, the definition ofall possible permutations and the execution of said function for eachconnection segment of each solution element becomes complex andespecially not performable in acceptable times, by using simplealgorithms.

In this case, the invention provides two possibilities:

-   -   In a first case, point distribution is generated on the basis of        a single fixed pattern or of a pattern selected among a        plurality of fixed patterns whereof the best solutions are known        and stored.

In a second case, point distribution is generated from time to time,e.g. on the basis of a random point generator and possibly incombination with means for checking that the different points havecertain mutual relations, defined by selection criteria, e.g. requiringthat the points do not fall all along a certain line, or too close toeach other or in overlapping positions. The selection or rejectioncriteria for the generated points may even allow a limited number ofpoints not to meet the selection criteria. In this latter case, theproblem is to be solved from time to time, wherefore the help of theso-called genetic algorithms appears to be useful.

Regarding the solution, other constraints may be established in additionto the simple connection of successive pairs of points by segments, toform a path passing across all the points, and having a minimum totallength. For instance, it is possible to limit the number of segmentscrossing the same point or prevent any segment crossover or limit thenumber thereof even out of the path. These additional constraints allowto considerably reduce the number of possible solutions since, referringto the illustrated embodiment, several solutions are removed which arepossible a priori but apparently illogical and impractical.

Regarding the illustrated embodiment, it is limited to four points tosimplify the explanation of the method, while it shall be understoodthat four points will not be sufficient for the method to have asignificant relevance.

With particular reference to the steps of the method, the latterconsists in converting the drawn graphical solution into a numericalsolution, i.e. in this case in computing the sum of the lengths of thepoint p_(n) connecting segments according to a sequence indicatedgraphically by the individual and based upon the known coordinates ofthe points p_(n).

At the same time as the graphical solution, the best solution is alsoprocessed, by mathematical computation. With the above four points, saidcomputation is trivial, there being only provided 24 possiblepermutations, some of them being identical. When a greater number ofpoints is provided, i.e. ten or thirty points, the solution shall beprocessed based on said genetic algorithms.

Hence, two absolute values are obtained, for the sums of the segmentsfor connecting the graphically selected sequence of points on the onehand and of the computationally defined point sequence on the other, thelatter minimizing the absolute value of said sum. Then said two valuesare compared to determine a deviation index between the graphicalsolution and the computed solution. This index is determined accordingto mathematical-statistical criteria, such as simple difference,relative difference, standard deviation, and other functions fordetermining the deviations between data. As a result, the method of theinvention provides a numerical value which is defined on strictmathematical bases and up to this step evaluation is totally objective.The evaluation result may be further interpreted against a scale forattributing, on an experimental or statistical basis, differentinterpretative evaluations of cognitive performances of the individual.The relation of the value obtained as a result of the method to theinterpretative evaluation scale may be also obtained by introducingpossible correction parameters depending on the demographic conditionsof the individual and on test performance conditions. This may be usefulto account for extreme cases, in which the individual has objectivedifficulties in performing the test, e.g. little or no familiarity withthe physical means required to draw the result.

The evaluation of the proposed graphical solution may also account forother different parameters, such as the time required to provide asolution, the occurrence of route discontinuities and even the choice ofsolutions which are too close to the reference solution.

Besides a personal skill test, or for instance a test for evaluating theskills of individuals for proper employment in a work situation, themethod of the invention may be also a help or indication instrument todetect pathological cognitive disturbances. In this case, the instrumentprovided by the method of the invention is not a diagnostic instrumentbut a simple indicator of the potential presence of cognitivedisturbances which may be possibly related to pathological conditions,yet to be diagnosticated by real appropriate diagnostic methods.

Referring to another improvement, the method of the invention includes apreliminary step which consists in solving a simplified form of theproblem, i.e. with a reduced number of points p_(n), e.g. thepreliminary step requires the method to be implemented with a ten pointproblem and later the method is implemented with a test problem based ona greater number of points, e.g. 30 points.

This preliminary step involving the execution of a simplified problemallows the user to get familiar with the apparatus and with the problem,to limit the occurrence of false solutions caused by a lack offamiliarity with the apparatus or by misunderstandings about the task tobe performed. In this situation, a deviation threshold may be definedbetween the drawn solution and the computed reference solution whereby,if the performance of the task in its simplified form, e.g. with tenpoints, provides deviation values below said threshold, the methodpasses automatically and immediately to the more complex problem, e.g.with 30 points.

If the first simplified execution results in excessively highdeviations, then there may be provided an automatic repetition of saidsimplified execution for a predetermined number of times. If deviationremains too high even after the execution is repeated a predeterminednumber of times, an intervention of the personnel in charge is required,because a potential misunderstanding or error situation is detected.

There may be multiple, even traditional apparatuses for implementing themethod of the invention, such as a simple paper sheet on which thepoints are drawn, for the individual to make connections to create thebest selected route. In this case, data may be visually read and enteredin a computer which contains the necessary programs to convert thegraphical/visual solution into a numerical solution and to compute thebest solution, i.e. the solution which minimizes the total routedistance.

FIG. 25 shows a block diagram of a preferred apparatus for implementingthe method and particularly with reference to the Traveling Sales PersonProblem.

The apparatus includes a processing unit, typically a CPU or a personalcomputer 1 wherewith several memories or a single memory divided intosections are connected. Memories or memory sections 2 to 7 contain theprogram for generating the two-dimensional space and for determining thepoints p_(n), the program for computing the solution on a mathematicalbasis, typically a so-called genetic algorithm, a program for displayingthe two-dimensional space and the points on a monitor or a displaydevice, a program for controlling the means for entering the point p_(n)connecting segments, a program for reading and displaying the drawnpoint p_(n) connecting segments.

Hence, the apparatus includes display means such as a monitor 3 or thelike and means 8 for entering segment drawing controls. Moreover, theapparatus includes means 9 for entering further data, parameters orcontrols, such as the number of points to be displayed. Additionalinterfaces may be also provided, such as a printer 10, a network adapter11 for connection to a central data storage system, means for datastorage on any type of storage media.

The above apparatus may consist of a traditional personal computer,wherein the input means are a traditional mouse or the like and thedisplay means is a traditional monitor. Instead of a traditional mouse,a pen-like mouse may be provided. The pen may be also associated with aso-called graphical table.

Regarding simplicity, especially for poorly educated users, a so-calledtouch screen device may be used as a display and input device, i.e. adisplay monitor whose outer surface is sensitive and acts as an inputdevice, operating either by direct touch or by the touch of a tool likea pen or the like.

The advantage of touch screens is considerable because these meansobviate the difficulties a user may have in test execution, when he/sheis not familiar with typical computer input means or the like. In thiscase, for instance, drawing operations are performed according toindications by touching the successive point to be connected to apredetermined starting point. Hence, the successive point connectingsegment is automatically drawn by the computer, which identifies fromthe coordinates the two points to be connected, that have been selectedby touching the image thereof.

According to a variant, the display screen 3 may be divided into twoparts 103, 203, one of which is used for drawing the route selected bythe individual, whereas the other part is used to display the stepselected through mathematical computation by the computer or through thecomputation algorithms loaded therein.

At the end of the task the two routes will be displayed in tiledposition on the screen, i.e. the one selected by the individual on agraphical/visual basis and the one computed by the computer.

Moreover, the computer will convert the graphical/visual solutionprocessed by the user into numerical data which are used to compare saidgraphical/visual solution with the computed one, therefore to determinean approximate value of the deviation between the two data.

Regarding the apparatus for implementing the method, it may be made inany manner and, as an alternative to the embodiment described above,which essentially involves typical personal computer means, it may becomposed of means specially designed for implementing the method, andparticularly with reference to the Traveling Sales Person problem.

Particularly, as regards the Alzheimer disease early screening andmonitoring method, a test as described in the following embodiment isprovided.

The “Traveling Sales Person problem” is an application for PC andMacintosh. The computer monitor must be at least 14 inches wide to allowan optimal perception of stimuli by the individual. Once the program isloaded and started, the screen shows two identical surfaces, one at theright side and one at the left side of the screen, each of 12 cm×14 cm.Both represent the field in which stimuli are identically distributed,which stimuli consist of points having a diameter of 2 mm. The testproposes a task wherein the individual is invited to draw the path, atthe right side of the screen, to lead him/her from one point to anotherand to more other points, until he returns to the starting point. Theroute is drawn by the tester following the indications of theindividual. The difficulty lies in that the route must be as short aspossible. Therefore, the independent variable being measured is thedistance, in km, run by the individual. If the right part of the screenis the part on which the individual draws the route, the left part isthe surface on which the computer, by using a genetic algorithm drawsthe ideal route, i.e. the one which runs the shortest possible distance.Two tests are provided, a running-in test and the real test, the formerbeing executed with 10 points, the latter with 30 points. The idealdistance is of 287,4203 km for the 10 point test and of 423,7406 km forthe 30 point test. The result is recorded in a fast and reliable manner,no paper document being required, but only a Powerpoint presentation inwhich the routes obtained by the individual and by the computer are“pasted”, and the deviation between the two is displayed.

An example of the administering procedure involves that individuals areallowed to sit in a room which may be darkened. The doctor or otherpersonnel, after introducing themselves and engaging the individual in abrief introducing conversation, show him/her the computer and ensure thescreen inclination and the room lighting allow an optimal vision ofstimuli. The instructions provided to the patient are as follows: “Startfrom any point on the screen and draw a route to connect all thesepoints until you get back to your starting point. The route should be asshort as possible. You will have no time limit. You will also be allowedto correct your route by moving backwards and restarting whenever youwish, until you will find the route that, in your opinion, is theshortest possible route to connect all the points.”

Once the understanding of the problem by the individual is verified, thefirst task is introduced, as a “run in”. The “run in” has a reducednumber of stimuli, i.e. points, e.g. 10. At the end of the task, theperformance of the individual is positively reinforced and theindividual is shown the ideal route, processed by the computer. The testresult, i.e. the route length, is measured in km and often, especiallyin the most serious cases and in the 30 stimuli test, the deviationbetween computer performance and individual's performance is very high.In these cases, it is more useful to ignore the numerical comparison andto simply show the different route run, insisting on the purpose ofdrawing a short route. After a brief pause, which may be used by thedoctor or other personnel to record performance, the real 30-stimuli,i.e. 30-point task starts. It is essential to repeat the instructionsfor the user, and to specify that the new task includes no longer 10,but 30 stimuli. The result is recorded once again at the end of theperformance, after allowing the individual to compare the obtainedresult with the computer result, provided the individual is interested.

With reference to a particular condition of test execution according tothe diagnostic method as proposed herein, it shall be noted that severalsolutions may be provided which are exaggeratedly close to the bestpossible solution being used as a reference. In this case, it must beconsidered that the individual who performed the test may suffer frompsychiatric diseases such as autism, or the like, which involveparticular skills in solving this type of problems, whereby the testmight be used not only to detect cognitive disturbances resulting inwrong or illogical solutions of the proposed problem, but also tosolutions which are surprisingly close to, or have a minimum deviationwith respect to the best reference solution. This does not mean a priorithat the individual suffers from these diseases, since from thestatistic point of view there is a non-zero probability that anindividual guesses the best possible solution, which may be even betterthan the one computed by a genetic algorithm. Nevertheless, thisprobability is really low and the simple repetition of the testgenerally results in completely different solutions. When theperformance repeatedly results in high level matches between theproposed solution and the best computed or known solution, then theresult provides an indication of a particular condition of theindividual who performed the test, which certainly requires furtherinvestigation.

1. A method for evaluating the cognitive performance of an individual byqualitative/quantitative analysis of the performance of a task,characterized in that: the task is a practical problem which may beexactly represented both graphically and mathematically and solved bothgraphically and computationally; the task has a set of solutions with anumber of elements greater than one, one element being the best possiblesolution; and wherein the individual provides a graphical solution; saidgraphical solution is compared with a known best reference solution andat least one difference index is determined between said best referencesolution and said solution proposed by the individual from saidcomparison.
 2. The method of claim 1, characterized in that the task isalways the same and the best reference solution is precomputed.
 3. Themethod of claim 1, characterized in that it includes two, three or moredifferent tasks, whose respective best reference solutions areprecomputed or known.
 4. The method of claims claim 1, characterized inthat the comparison between the best reference solution and thegraphical solution of the individual may be only performed on agraphical basis, or both solutions may be converted into a numericalresult or a set of numerical data to be compared with each other.
 5. Themethod of claim 1, characterized in that a different problem is definedfrom time to time, the graphical solution determined by the individualbeing converted into a numerical solution and later compared with thecomputed reference numerical solution, a difference index between thebest computed solution and the solution proposed by the individual beingcomputed from said comparison.
 6. The method of claim 5, characterizedin that the different tasks are characterized by a certain number ofvariables which are randomly generated every time.
 7. The method ofclaim 1, characterized in that the problem is such that it has a set ofsolutions, consisting of a plurality of solutions, at least one of whichis the best or correct solution of the problem.
 8. The method of claim7, characterized in that the set of solutions has a discrete and finitenumber of solutions.
 9. A The method of claim 1, characterized in thatthe difference index between the solution proposed by the individual ona graphical basis and the computed reference solution is a function fordetermining the deviation between two values, among which particularlythe absolute difference or relative difference values, or the deviationvalue, such as the standard deviation.
 10. The method of claim 1,characterized in that a set of rules is provided, i.e. delimitingconstraints, to provide the graphical and/or computational solution,which may be applied to a different extent and in differentcombinations.
 11. The method of claim 1, characterized in that eachsolution has more variables or solution parameters, one or more of whichparameters or variables may be compared with the corresponding ones ofthe best solution or with other reference parameters for determiningcognitive performances.
 12. The method of claim 1, characterized in thatthe proposed problem is such that it has a set of solutions, whoseelements consist each of one or more possible combinations of differentsolving steps p_(n) which may be executed in different execution orders.13. The method of claim 12, characterized in that the set of solutionsmay consist of solution elements each comprising one of the possiblepermutations of the steps p_(n) within a succession or sequence ofsteps.
 14. The method of claim 1, characterized in that the proposedproblem has at least one difficulty adjusting or setting variable. 15.(canceled)
 16. The method of claim 14, characterized in that saiddifficulty setting parameter comprises the number of steps, hence thenumber of permutations of said possible steps which is equivalent to thenumber of solution elements of the set of possible solutions, therebeing provided at least one best or correct solution element and/or thedefinition of additional solution determining rules, i.e. thedetermination of delimitation constraints.
 17. The method of claim 1,characterized in that the solution elements consist of a function of thesteps p_(n) or of an operator on said steps, which takes differentvalues depending on the sequence which orders the execution of the nsteps p_(n).
 18. The method of claim 17, characterized in that thisfunction is selected in such a manner as to be an easily executablemathematical and graphical operation, whereas the difficulty is definedin the increasing number of possible permutations of executions of stepsp_(n).
 19. The method of claim 1, characterized in that the problemproposed is of such a type that each preceding steps qualitatively andquantitatively affects at least the next step, and/or even severalsucceeding steps.
 20. The method of claim 1, characterized in that itinvolves the performance of tests for calibrating a scale or a table tointerpret the deviation or difference index between the value of thesolution given by the individual and that of the computed referencesolution.
 21. The method of claim 1, characterized in that it includesthe performance of at least a first step and at least a second step, thefirst step being a familiarization step in which the problem isintroduced in a graphical/visual manner, the problem is solved by agraphical/visual instrument, a reference solution is simultaneouslycomputed with a mathematical method; the graphical/visual solution isconverted into a numerical solution and the graphical/visual solutionand the reference solution are compared, with a deviation index beingdetermined between the two, based on the simplified problem, and anevaluation step, in which said operations are performed on the basis ofa problem set on a higher difficulty level.
 22. The of claim 21,characterized in that a reduced number of steps is provided in thefamiliarization step, as compared with the evaluation step.
 23. Themethod of claim 21, characterized in that a deviation threshold isestablished, and the familiarization step is repeated as long as thedeviation determined in said familiarization step is not below saidthreshold or for a predetermined number of times before passing to theevaluation step.
 24. The method of claim 1, characterized in that theproblem is the so-called Traveling Sales Person Problem, in which a listof sites, distributed over an area, is defined, which sites havedifferent locations and must be visited in succession, along such aroute, i.e. such a sequence or succession of location hits that thetotal length of the route is minimized.
 25. The method of claim 24,characterized in that an at least two-dimensional space is defined,wherein the locations are defined by points distributed over this space,whereas the graphical solution consists in drawing the route to minimizethe global length thereof, in the form of point connecting segments. 26.The method of claim 24, characterized in that the mathematicaldescription consists in the definition, by an at least two-dimensionalreference system, of the different locations, in the form of at leasttwo coordinates for each location, whereas the solution of the sequenceof connection segments between individual points is computed on thebasis of the numerical determination of the sum of the lengths ofsuccessive point connecting segments, according to the point connectingsequence which provides a minimum value of said sum of the connectingsegments.
 27. The method of claim 26, characterized in that, in order tocompute the sum of the point connecting segments according to a pointsequence which minimizes this sum, so-called genetic algorithms areused.
 28. The method of claim 24, characterized in that thegraphical/visual solution of the problem in a purely graphical modeconsists in drawing point connecting segments in a selected connectionsequence.
 29. A The method of claim 24, characterized in that theconversion of the graphical solution into a numerical solution isobtained by computing the length of the connection sequence, which isselected when the point connecting segments are drawn.
 30. The method ofclaim 24, characterized in that it has at least one, two or moredifferent fixed point distribution patterns, said points representingthe sites to be visited and the corresponding best solution is providedfor each point distribution pattern.
 31. The method of claim 24,characterized in that points, which represent the locations to bevisited, are determined on the basis of random number generatingalgorithms, wherewith at least two coordinates are defined for eachpoint and the best reference solution is determined from time to time.32. The method of claim 24, characterized in that the parameters forcomparing the user-supplied graphical solution with the known solution,are the total length of the two routes and/or the number of crossoversand/or the connecting segments passing through each point and/or thepresence of route discontinuities and/or the execution time.
 33. Themethod of claim 24, characterized in that it includes the followingsteps: defining an at least two-dimensional space according to apredetermined coordinate system; defining the number of points to bedistributed in said at least two dimensional space; uniquely identifyingthe position of each of said points distributed over said space with atleast two coordinates determined by random generation; displaying agraphical representation of said at least two-dimensional space and ofthe points distributed thereon; generating a succession of pointconnecting segments in a point connection sequence selected in such amanner as to minimize the total length of the sum of the individualsegments connecting successive pairs of points of said point connectionsequence, only based on visual evaluation; determining the sum of thesegments connecting successive pairs of points, on a graphical/visualbasis, based on the graphically defined point connection sequence;comparing the graphically defined total sum of the point connectingsegments, with the total sum of the connection segments of a bestreference solution, i.e. a point connection sequence through segments,which minimizes the total sum of the point connecting segments, anddetermining a difference index based on deviation measurementalgorithms, such as absolute difference, relative difference and/orstandard deviation and/or other algorithms for estimating differencesbetween values. said reference solution being known and precomputed orcomputed while the graphical solution is provided.
 34. The method ofclaim 24, characterized in that the deviation or difference indexbetween the graphical/visual solution and the computed referencesolution is interpreted by comparison with an experimentally establishedcalibration table or scale.
 35. The method of claim 1, characterized inthat it provides that the reference solution be graphically displayed.36. The method of claim 1, characterized in that it includes thegraphical/visual comparison of the reference solution with the onedetermined in a graphical/visual manner by overlapped and/or tileddisplay of the two solutions.
 37. The method of claim 36, characterizedin that it provides that the coincident connection segments in the twosolutions be highlighted with respect to non-coincident connectionsegments.
 38. The method of claim 36, characterized in that it providesthat the two solutions be displayed in different colors fornon-coincident segments, whereas coincident segments are displayed inthe two colors selected for displaying the two solutions, or in a thirdcolor.
 39. The method of claim 24, characterized in that it includes afamiliarization step, providing a reduced number of points to beconnected, as compared with the number of points provided in theevaluation step.
 40. The method of claim 1, characterized in that itincludes the determination of factors for weighting the graphical/visualsolution and/or for decreasing/increasing difficulty to correct or adaptto specific extreme conditions of individual-related demographicparameters.
 41. A method for early screening and monitoring of Alzheimerdisease, characterized in that it has characteristics as recited inclaim
 1. 42. A method for business applications, characterized in thatit has one or more characteristics as recited in claim
 1. 43. A methodfor evaluating the cognitive performance of an individual, with themethod of claim 1, characterized in that it comprises: a screen (3, 103,203) displaying an at least two dimensional area and points distributedover said area; means (8) for drawing segments to connect pairs of saidpoints by means of connection lines to be displayed on said screen; anelectronic processing unit (1) with a memory (2, 3, 4, 5, 6, 7)containing the algorithms for generating the at least two-dimensionalspace and for generating the coordinates of the different locations, thealgorithms for generating a graphical representation of the at leasttwo-dimensional area and of the individual points, the algorithms fordrawing the point connecting segments and for displaying said connectingsegments on the screen, the algorithms for determining the total lengthof the drawn segments and the algorithms for pure mathematicalcomputation of all the point connecting segments, in a connectionsequence which minimizes the total length of said segments, as well as apossible algorithm (103, 203) for alternately or adjacently displayingall the point connecting segments, as obtained from the algorithm forcomputing the reference solution, and as set by the individual in thegraphical/visual solving attempt.
 44. The apparatus of claim 43,characterized in that it comprises means for overlapped display of allthe drawn successive point connecting segments and all the computedsuccessive point connecting segments, the segments from the twodifferent sets, i.e. the drawn set and the computed set beinghighlighted in different manners, e.g. in different colors, and thecongruent connecting segments from the two solutions being highlighted,for instance with two-color, double or three color segments.
 45. Theapparatus of claim 43, characterized in that it also includes memoriescontaining one or more programs for determining a quantitativedifferentiation index between the drawn and the computed sets ofsegments and/or between corresponding total lengths.
 46. The apparatusof claim 43, characterized in that it includes memories containinginterpretation criteria based on empirically or experimentallyestablished data tables, and means for comparing the differentiationindex with said interpretation tables.
 47. The apparatus of claim 43,characterized in that it includes a memory or a memory section designedfor collecting and storing the sets of segments drawn by a uniquelyidentified individual when graphically solving different problems withdifferent point distributions, there being provided algorithms fordetermining an average differentiation index based on the individualdifferentiation indexes between the drawn set and the computed set, asdetermined during the execution of the different successive tests. 48.The apparatus of claim 43, characterized in that it includes memoriescontaining data for characterizing the typical data of the individualwhich have a potential influence on the test execution and may used todefine parameters for weighting the differentiation indexes to accountfor any particular specific skills of the individual in extremeconditions.
 49. The apparatus of claims 43, characterized in that allthe means consist of a personal computer and typical devices therefor.50. The apparatus of claim 43, characterized in that it includes means(8) for highlighting the two points to be connected and means (1) forautomatically drawing the segment connecting the two highlighted points.51. The apparatus of claim 43, characterized in that the display meansconsist of a screen of the so-called Touch-screen type, i.e. having theadditional function of an input device, operated by the touch of a handor a tool on the screen.
 52. The apparatus of claim 43, characterized inthat it is an apparatus for performing Alzheimer disease screening ormonitoring tests as claimed in claim
 41. 53. The apparatus of claim 1,characterized in that it is an apparatus for implementing the method inbusiness applications as claimed in claim
 42. 54. The method of claim 1,characterized in that it is a method for screening or monitoringneurological and/or psychiatric disturbances, such as autism or thelike.
 55. The method of claim 43, characterized in that it is anapparatus for screening or monitoring neurological and/or psychiatricdisturbances, such as autism or the like.
 56. The method of claim 1,characterized in that it includes several evaluation steps, each beingbased on the comparison between the proposed by the individual and adifferent solution computed by means of one of the various possible bestsolution computation algorithms, and/or a different best solution amongthe existing solutions, the comprehensive evaluation consisting of acombination of said evaluation steps, possibly appropriately weighted.57. The method of claim 1, characterized in that several parameters maybe provided, alternatively or in combination, for comparing the solutionproposed by the individual with the best reference solution, whichsolutions may be, alternatively or in combination, the number ofcrossovers or hits through one point, the solving time, the path segmentdrawing order, the determination of the areas of polygons defined bydrawn segments and by crossovers and/or the determination of thetotal-area of the surface enclosed by the drawn path, as well ascomparisons between said two area values or other characteristics of thesolution to be parametrized graphically or mathematically.